There's a scene towards the end of Steven Spielberg's epic Close Encounters of the Third Kind when a number of alien abductees disembark the mothership. As they're met by military officials, the following exchange is heard:
"They haven't aged a day. Einstein was right."
"Einstein was probably one of them."
So, bearing this in mind, take a look at this picture of Richard Dreyfuss, in character as the film's leading man Roy Neary.
Now skip forward 37 years to the release of Marvel's Guardians of the Galaxy, featuring the excellent Chris Pratt as Peter Quill, otherwise known as Starlord.
Compare. Contrast. They are clearly the same person.
Neary went voluntarily into the alien craft, and nearly four decades later, having not aged a day, he's flitting around with a raccoon and a tree completely shitting up bad people after taking on the Starlord identity. He's also worked out a lot and turned into a roving space git, but the boredom of endless space travel does that to a man.
It's the only logical explanation and fits entirely to the narrative I've made up completely in my head, and for those of you of a scientific bent, this is the final, conclusive proof of the Theory of Relativity.
Einstein was right.